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Relentless PING!

PostPosted: December 9th 2010, 5:10pm
by Freakist
Hey! Hi! Howdy!
92 EXT AWD. Motor installed from 94-95 Blazer, 4.3Vin W. Ran like scalded cat till maybe a month and a half ago. In fact, still does, but is slurping down gas worse than a carburated Ford 460, and that's not funny.
Starts quick and idles generally very smooth. Problem appears to hit when it enters closed loop mode after warming up. Absodamnedlutely relentless ping above idle rpm, but only in gear.The freakin thing plain ol SINGS when it is in park or neutral, no ping, very responsive. Gas mileage in the toilet, about 9 MPG or so. Ping not noticeable with foot in it, good acceleration. I'm starting to hear noises I really don't like when I am in gear hitting the gas with the brake on to see if the latest "improvement" has lessened or eliminated the ping, yet those more ominous sounds come and go. I don't want to acknowledge their existence by name unless it's undeniable.
After a year of driving on swapped motor, changed gear ratios to 3.42 from 3.73, to give better mileage on highway.In June 2010, drove vehicle to San Diego from Colorado Springs and back, only minor issues, did however overfill my transmission in the dark parking lot of Walmart in Grand Junction. Drained out some the next morning at a car wash; no apparent damage to trans, it is a 2007 crate 700r4, works real good. Mileage was around 14 on highway as there were a ton of vicious hills on US24 and I was incredibly overloaded, and had not yet changed my DRAC so the speedo read 7 percent SLOWER than actual, as expected, vehicle performed well with original module still being applied to computer. replaced drac & module (and eventually the entire computer) with units from identical drive train (GU6 3.42 ratio) computer, from 92 astro, and that's what it has in it now.
A list of all the things swapped out with working spares (or junkyard replacements) or bought new in an effort to save the favorite of all the vehicles I've ever had:

First, swapped in spare fuel pressure regulator. passenger side did look a little cleaner than it was supposed to be; no help. Tests 64 psi key on, drops to 58 and stays above 50 for at least an hour, tested several times.
Fuel injection system swapped for one from the original motor, 2 years old at swap, no difference in ping or mileage.
Swapped EGR from junkyard, no effect, no codes
SEAFOAMED the motor. No help at all.
swapped both knock sensors from previous engine spare pile. all 4 test at 8.1 ohms, code 42 & 43 go away.
replaced Intake air temp sensor, code 23 went away, probably caused by inadvertent start of engine while sensor unplugged due to installing aftermarket air cleaner.
Replaced Ignition module, cap, rotor and wires, all new, performance, eliminated light show, so far as I have observed. Cleaned platinum plugs, which look very nice, all to no effect whatsoever.
Swapped computer(ECM) from aforementioned 92 astro (a lucky junkyard arrival), this leaves me in EXACTLY the same boat. 3 days later, normal driving, code 43 reappears. problem traced to sensor failure (the small diameter thread version, screwed into the back of the drivers side head), though the ohms still look good. swapped the other one back in.
The thing runs GREAT when you first start it, has small hesitation and progressively louder ping after closed loop (ESC?) starts, depending on engine temperature. ping noise is only evident between approx. 5-10% to maybe 20-25% pedal travel. whatever the actual percentage, it is remarkably constant from one pedal depression to the next. If you romp it the ping duration is very short as engine rpm build and the thing does pretty well on the highway by any standard, except for what is happening to all this fuel? The oil is not wasted, the exhaust is not black, the pump is new and holds pressure, and I don't seem to have any leaks. No O2 sensor codes, no fouling of the plugs,
This is blowing my mind and I will have to sell it and buy a bicycle real soon, I'm not joking.
THINGS I NEED TO KNOW:
can an egr, or even more unbelievably 2 egrs die or leave the valve shut and throw NO CODES?
The ACTUAL MEANING OF THE CODE 43 IS WHAT? Is it that the voltage has been too high or low for 20 seconds, or is it that the ECM has gotten a steady ping signal for 4 seconds or more? When it recently threw code 43 it was noticeably attempting to retard the timing just before throwing the ses light on for a few seconds, as I was easing out of a 7-11 parking lot, part throttle, pinging like mad as has become usual. I get differing info online, need some authoritative input.
If the 2 different fuel injection spiders and regulators were both leaking identically, could the o2 sensor fail to detect that I'm using 50 percent more gas than usual or throw NO CODE AT ALL?? Come on, whats up with having a computer if it can't tell your burning this much extra?
On the other hand, wouldn't my exhaust look black, wouldn't the engine stumble on that volume of fuel? and with that kind of fuel usage, how could this actually be spark knock? I thought it had to be pretty lean for that to happen at all. how could I have replaced so many things and STILL not made a dent?
Could the CAT cause ping? and only at a certain rpm range? The exhaust appears to flow freely, and the midas guy did a great job 2 months ago.
Could the fuel issue and the ping be separate issues? I'm tellin ya EVERYBODY that rode in this van for the last 2.5 years has a comment on how smooth it runs (Even now!), and how strong it accelerates. Not like I'm an overactive leadfoot or anything... really! I do like to go fast yet I take extreme care of my engines.
MIND BLOWN. :banghead:

Lil Help?
PLEASE?